TeX Gyre Termes' ligatures work in LuaLaTeX, but fail in XeLaTeX

Question

I recently installed TeX Gyre Termes, and I noticed that ligatures were present when I compiled with LuaLaTeX, but not with XeLaTeX:

% !TeX program = XeLaTeX
\documentclass{article}
\usepackage{fontspec}
\setromanfont{TeXGyreTermes} % no spaces in name

\begin{document}

fi ff fl ffi

\end{document}

XeLaTeX:

LuaLaTeX:

The same problem arises with small caps- in LuaLaTeX, all works well, but upon switching to XeLaTeX, small caps disappear, and XeLaTeX warns me that it must substitute with normal TeX Gyre Termes instead of small caps. I suspect that the issue is related to my installation of TeX Gyre Termes, as ligatures are present when other fonts are used. However, I have tried re-installing TeX Gyre Termes multiple times, but this issue persists.

Therefore, my question is: because I am unable to use a functional copy of TeX Gyre Termes, and because XeLaTeX compiles faster than LuaLaTeX, what can I do to ensure that ligatures appear when I compile with XeLaTeX?

(I do not want to switch out TeX Gyre Termes with another Times-like font, as I prefer its italic best. However, I do not care whether the OpenType version of the font is used or not.)

This question seems related: What are the incompatibilities of pdftex, xetex and luatex? However, it does not discuss the reason behind this difference, and what may be done about it.

Answer 1

xelatex and lualatex use different methods to search for fonts. xelatex uses fontconfig, lualatex (or more precisely the package luaotfload used to load fonts) has its own database.

This means that sometimes the one engine finds a font but not the other depending e.g. on spaces or uppercaseing(lualatex don't care, while xelatex is rather picky).

My guess is that one your system xelatex is finding a type1 font when you use the name without spaces. You could add \XeTeXtracingfonts=1 and check the log-file, to confirm this guess.